byteduck
Add aarch64 support
I've wanted to port duckOS to another architecture besides outdated 32-bit x86 for a while now - and I've settled on starting with aarch64 for the ultimate challenge :)
I'm on a bit of a deadline here in terms of when I start my new job and thus have to stop working on duckOS, so this'll be fun.
Don't expect anything to compile or run yet, this is extremely WIP.
Hi Aroon, it seems a really cool challenge!
Just for curiosity: Are you going to port duckOS to a specific SBC or qemu-virt? Where do you find the technical specifications for the arch/board?
I'm following you very interested
Are you going to port duckOS to a specific SBC or qemu-virt?
I'm gonna be honest - I haven't done a ton of research into specifics yet. I'm going to start with a generic qemu aarch64 target, and if I can, I'd love to get it running on a Pi 4.
My method is to learn by doing, so I'm just crossing bridges as I get to them - my new job will involve lots of arm64 kernel work, so I suppose this is my way of giving myself a crash course :)
Mmmh, aarch64 kernel as a job... I smell an Apple inc. job here :)
Good job man!
It lives! (Sort of). We can boot, initialize MiniUART for output, drop to el1, and access the framebuffer. Still not even close to functional yet - still no MMU, interrupts, exceptions, kbd/mouse, tasking, etc. Most of the work so far has been refactoring architecture-dependent stuff in the kernel and getting the dang thing to compile :)
I have decided to start with targeting the RPi 3b since qemu has a machine preset for it, there's tons of documentation, and I already have one. From there, targeting the Pi4 should be pretty simple since it uses a similar Broadcom SOC I believe.
After days of agony, it boots on real hardware! Turns out QEMU doesn't emulate a lot of the fun hardware quirks, but armed with nothing but a UART cable and time for lots of trial and error, I eventually got it working on a real RPi 3b. We can now use memory management through the normal mechanisms, meaning the way is paved to start getting the fun stuff going! Up next are interrupts and tasking.
Hi Aroon, do you think you will also be able to implement mouse and keyboard input?
Great Work!
do you think you will also be able to implement mouse and keyboard input?
I should be able to - I haven't looked much into it yet, but I assume doing so will involve setting up a USB stack. It's simple on the PC platform because you can use the PS/2 controller as a fallback mode even if the M/K are USB, but I don't believe the RPi has any sort of equivalent, so I'll need to implement a USB stack and a USB HID driver. I could be wrong though.
Unfortunately, life has been pretty busy with moving and all sorts of other stuff, and I've run out of time for now. I'll merge what I have so far, just so it's there :) I'm at least glad I was able to get some basics done.